To allow operations of unmanned aerial systems (UAS) in the national airspace, highly reliable means and methods are necessary to assure that UAS do not enter airspace from which it is restricted/prohibited, collide with and/or otherwise interfere with the operations of manned aircraft. However, in meeting this need the cost and complexity of UAS must be kept reasonable in order to facilitate their commercial viability.
A common limitation given in a Certificate of Waiver or Authorization (COA) requires a UAS to specifically avoid airports by a distance of at least five nautical miles. This area around the airport is intended to act as a buffer to keep the UAS away from any manned aircraft that may be flying in the airport traffic pattern. Since there is no actual physical barrier, a wayward, whether accidental or intentional, UAS can still cross this buffer and relatively quickly be in close proximity with manned aircraft. As a result, such a buffer may mitigate the likelihood of a midair collision, but ultimately cannot act to prevent it. More specifically, nothing physically prevents the UAS from being involved in a potentially fatal midair collision with a manned aircraft in the airport traffic pattern. Since the worst credible result of the midair collision hazard is a fatality, this hazard would be assigned a “catastrophic” criticality.